Apparatus for bleaching flour



Dec. 26, 1944. MDoNALD 2,365,757

' APPARATUS FOR BLEACHING FLOUR Original Fild May 3, 1941 2 Sheets-Sheet l Dec.26, 1944. MCDONALD 2,365,767

/ APPARATUS FOR BLEACHING FLOUR Original Filed May 3, 1941 2 Sheets-Sheet 2 jnvefl/zor Patented Dec. 26, 1944 v UNITED STATES PAT NT? oFF E:

APPARATUS FOR BLEACHING FLOUR Hugh McDonald, Minneapolis, Minn., assignor to Pillsbury Flour Mills Company, Minneapolis,- Minn., a corporation of Delaware Original application May a, 1941, Serial Nb.

391,735. Divided and this application ber 21, 1942, Serial No. 459,109

4 Claims.

This invention relatesto apparatus for bleachiriiig1 flour and other analogous powdered mate- This application is a division of my United States application for patent entitled Process for bleaching flour, Serial No. 391,735, filed May 3, 194i, now Patent No. 2,307,631, issued January 5, 1943.

' flour stream.

It is an object of I the present invention to provide a novel and improved apparatus for bleaching flour wherein a gaseous bleaching medium is used, the apparatus being so constructed as to thoroughly and intimately bring the bleaching gas into contact with the line particles of the flour to produce a uniform and thorough bleaching action with neither over-treatment nor under-treatment.

Another object is to provide a-novel and improved bleaching apparatus for flour which can be operated continuously without shut down periods and without the necessity for cleaning out the apparatusand which will eliminate the possibility of lumps of over' bleached flour passing to .the flour stream from the bleaching apparatus.

The objects and advantages of the present invention will more fully appear from the follow- Septeming the lower adjacent part of the feed spout in dotted lines.

Referring to the drawings, a typical apparatus made in accordance with the present invention I is shown. This bleaching machine includes a large drum designated as-an entirety by the letter' A and having an upper cylindrical portion 6 closed at its upper end by a cover plate I. The lower end of the cylindrical portion '6 of the drum is connected to two dividing trunks 8' each of which has outer half conical walls to and inner walls 8b which extend downwardly from a transverse medial line running fore and aft of the drum A at the lower part of the cylindrical portion 6 and which walls 8b are also curved in horizontal cross section and taper from their upper edges to, their lower edges. The walls of the dividing trunks 8 are quite steep so as to prevent the lodging of flour thereon. At their lower ends the dividing trunks are of elliptic shape as shown in Fig. 4. and they join collecting trunks 9 at their lower ends which collecting trunks run down diagonally toward each other to join and form an outlet mouth It. This mouth Ill delivers into a horizontally disposedcylindrical ing description made in connection with the ac- I companying drawings, wherein like reference characters refer to. the same or similar. parts throughout the various views, and in which- Fig. 1 is a view in front elevation of an apparatus made in accordance with the present invention;

Fig. 2 is a view in side elevation of the same apparatus; Fig. 3 is a plan view of the said apparatus; Fig. 4 is a horizontal section taken on the line 4-4 of Fig. 1 as indicated by the arrows;

Fig. 5 is a vertical section taken on enlarged scale on the line 5-5 of Fig. 2 as indicated by the arrow; and

conveyor casing H which runs to one side of the drum fAf and is in turn equipped with an outlet 12. The central portions of the walls at of the dividing trunks are not joined and a boxlevel of the lower end of the chute is capable of adjustment. A bracket I5 is secured to the two walls 8b below the box-like bracket l3 and the bracket l3 carries on its upper side a thrust bearing It within which an upwardly extending vertical shaft H is journaled. This shaft ll is also journaled in a bearing 18 secured to the undersideof the top of the box-like bracket It. The shaft is packed by packing it at the point where it emerges from the box-like bracket it and the shaft extends upwardly to a point ad- Fig. 6 is a detail in still larger scale illustrating the rotating dish in vertical section and showto but spaced upwardly somewhat from the bottom of the dish.

Secured to the their" below the dish is a large fan 22 the blades of which are pitched relative to the direction of rotation of the shaft so that the fan will force a blast upwardly from below the dish 20. A pair of gas pipes 23 for the admission of bleaching gas are mounted in the top plate "I ofthe drum and these pipes are supplied with the bleaching gas from any suitable source of supply as through hoses 24. Gases that may be employedfor the purpose are chlorine, nitrogen trichloride, oxides of nitrogen etc. audit is contemplated that one or a mixture of such gases will be used in connection with the present machine.

In order to suitably support the drum "A" a stand consisting of four legs. 25, side cross bars 28 and front and rear cross bars 21 is provided,

said legs being attached by suitable brackets 28 to the dividing trunks 801' the drum A. At the front of the machine a driving shaft 28 is provided and this shaft is joumaled in suitable bearings 30 carried by the two front legs 26. This shaft is adapted to be driven as by a belt (not illustrated) from any suitable source of power and the belt will run over a pulley 3| carried by the shaft 28 at one end thereof. The shaft 29 is located adjacent the lower end of the shaft l1 and the shaft 28 carries a vertical pulley 32 over which a belt 33 travels, this belt also running over a horizontal pulley 84 carried a,see,7er g I another in detached relation to bring the bleachby the shaft 11 between the walls 8b adjacent the lower end of the shaft.

Journaled in a bearing 35 carried by the side bars 26 and also journaled in suitable bearings 36 carried at the ends of the conveyor casing II is ahorizontal conveyor shaft 3'! which ex-' tends from the left side of the machine as shown in Fig. 5 through the conveyor casing ii. This shaft is "driven from the left end of the shaft 29 as viewed in Fig. 1 by means of a pulley 38 carried by the 'shaft 28, a pulley 39 carried by the shaft 21 in ,alignment with the pulley 38 and an endless belt 40 running over the two pulleys 38-and '38. Within the conveyor casing II the conveyor shaft 31 carries a plurality of pitched vanes 4| and the direction of rotation of the shaft 31 is such relative to the pitch of the vanes 4| that these vanes will work the flour fromthe mouth Hi to the mouth l2. Extending into the conveyor casing II from the mouth III is a partition 42 which runs downwardly 4 across the upper portion of the casing to a point .the dish 20. The dish 20 rotates at high speed runs 'ing gas introduced into the top of the drum into intimate contact with the individual flour particles, whereby the flour is rapidly bleached. The bleached flour falls into the dividing trunks 8 and is then collected by the collecting trunks 9 to discharge from the mouth l8 into the conveyor casing The conveyor, consisting of the shaft 31 and the vanes 4|, is rotated at such speed relative to the quantity of flour delivered thereto that, the flour in the casing II will always'more than half fill the conveyor casing the right, as viewed in Fig. 5, and dischargedthrough the outlet mouth |2.

With the arrangemelit shown the flour is broken up into a fine shower with the individual particles in detached relation and acted on by bleaching gas and it delivers out of the drum A" without in any way clinging to the drum.

By reason of the fact that. the flour cannot cling 'ment or under-treatment of any p rt of the For certain types of flour it may be deslrable to vary the spacing of the lower end of k the chute l4 relative to the dish 28' and for this purpose the extension Ha of the chute is made adjustable upwardly and downwardly relative to the main part of the chute.

It will be seen that a highly eiilcient bleaching machine has been provided. Various changes may be made in the form, details, arrangement and proportions of the-various parts 4 of the bleaching machine without departing and as the flour is received by the dish it is-t thrown ofi centrifugally by the dish and the serrated teeth 2| act in throwing of! the flour to break it up and divide it. The fan 22 working below the dish 28 throws up a'blast into the flour thrownout centrifugally by the dish z'l-endthis blast further divides the flour into .-.'a fine shower or dust cloud wherein the individual flour particles are spaced one from from the scope bf the invention which generally stated consists in the matter shown and described and set forth in the appended claims.

What is claimed is: I -1. A machine for bleaching flour comprising a closed upright drum having means for collecting and removing the treated flour from the lower portion thereof, means for continuously discharging flour from the central portion of said drum and at a level some distance below the top of said drum, ,a centrifugal rotary distributor of' slightly greater area than the cross sectional area of said discharge means mounted below said flour discharge means and receiving therefrom and con; structed to cause the flour to be finely divided and thrown out centrifugally and somewhat u'p- "wardly therefrom, means for discharging a bleaching gas within said drum and a fan disposed some distance below both of said distributor and said gas discharge arid of several times the diameter of said distributor for directing a blast upwardly into the distributed flour and .into and against the bleaching gas introduced.

2.'A flour bleaching machine comprising a closed upright drum, means for discharging a bleaching gas within said drum, 9. fiour delivering medium having a downwardly directed discharge disposed substantially axially within said drum at some distance below the top of said drum, a centrifugal, rotary distributor mounted axially a short distance below said discharge and constructed to finely divide and throw out centrifugally and somewhat upwardly a shower of flour particles in the upper portion of said drum, said distributor having an area somewhat greater than the cross sectional area of said discharge but relatively very small to the cross sectional area oi. said drum, a fan independent of said distributor but mounted co-axially thereof in spaced relation some distance below said distributor and having a diameter several times the diameter of said distributor and constructed to set up from below said distributor an upwardly moving current of air into the shower of finely divided flour in the upper portion of said drum,

means for driving said fan and said distributor ugal, rotary distributor in the form of a shallow dish mounted axially a short distance below said discharge and-constructed to finely divide and ..throw out centrifugally and somewhat upwardly a shower of flour particles in. the upper portion of said drum, said distributor having an area somewhat greater than the cross sectional area of said dischargebut relatively very small to the cross sectional area of said drum, a fan independent of said distributor but mounted coconstructed to set up from below said distributor an upwardly moving current of air into the shower of finely divided fiour in the upper portion of said drum, means for driving said fan 7 and said distributor and means at the lower end of said casing for removing the treated fiour therefrom.

4. A flour bleaching machine comprising a closed upright drum, means for discharging a bleaching gas within said drum, a flour delivering medium having a downwardly directed discharge disposed substantially axially within said drum at some distance below the top of said drum, a centrifugal, rotary distributor mounted axially a short distance below said discharge and constructed to finely divide and throw out centriiugally and somewhat upwardly a shower oi flour particles in the upper portion of said drum, said distributor having an area somewhat greater than the cross sectional area of said discharge but relatively very small to the cross sectional area of said drum, a fan independent of said distributor but mounted co-axially thereof in spaced relation some distance below said distributor and havinga diameter several times the diameter of said distributor and constructed to set up from below said distributor an upwardly moving current of air into the shower of finely divided flour in the upper portion of said drum, means for driving said fan and said distributor, means at the lower end of said-casing for remov ing the treated flour therefrom, the lower portion of said drum being constructed in the form of two downwardly extending trunks disposed below said fan and means at the lower ends of said trunks for removing the treated flour therefrom.

-HUGH MCDONALD. 

